The Democratic Party is suing Republican presidential nominee Donald Trump, state GOP officials and campaign surrogate Roger Stone for alleged voter intimidation tactics in four separate states, Reuters reported on Monday, in an effort to end poll-watching programs GOP officials say protect against voter fraud and Democrats say are a form of illegal racial intimidation.

Democrats filed the suits in the states of Pennsylvania, Nevada, Arizona and Ohio, writing "Trump has sought to advance his campaign's goal of 'voter suppression' by using the loudest microphone in the nation to implore his supporters to engage in unlawful intimidation." They specifically accused Trump and the GOP of violating the Voter Rights Act and Ku Klux Klan Act.

Trump has launched a campaign "election observer" program ostensibly intended to offset what he has continually referred to as a "rigged" election (in-person voter fraud is actually nearly nonexistent in the U.S.). As NBC News noted, this program has generated alarm among progressive watchdogs who understand his allusions to "certain areas" in which supposed fraud will happen as a racial dog-whistle.

Trump first began sounding this alarm in earnest in August, when he exhorted his supporters to do "you know what" at the polls on Nov. 8. Notably, the GOP nominee has brought up the subject significantly more as he slipped in the polls in the ensuing months.

According to Reuters, Democrats targeted Stone for a separate lawsuit over his "Stop the Steal" exit-polling program, which they said was part of an effort to intimidate minority voters. The website for the program says Democrats "intend to flood the polls with illegals. Liberal enclaves already let illegals vote in their local and state elections and now they want them to vote in the presidential election."

Legal scholar Rick Hasen wrote on his blog the suits likely target behavior too vague to compel courts to act, but may "bring publicity to" and generate public pressure against "the activities" before the election.

Each of the four states in question is an important battleground in the Nov. 8 elections. According to polls on FiveThirtyEight, Trump holds projected leads in Arizona and Ohio, while Clinton leads by large margins in Nevada, Pennsylvania.